Electrode adjustments means for mercury cathode electrolytic cells



June 25, 1968 R. M. COOPER ET AL 3,390,070

ELECTRODE ADJUSTMENT MEANS FOR MERCURY CATHODE ELECTROLYTIC CELLS Filed Feb. 19, 1965 5 Sheets-SW61 l I Z0 0 Z6 Z0 L I s FIG-I INVENTORS. ROY M. COOPER. WILL/AM c. GA RDINER BY JAMES RNEWBE'RR) AGENT J1me 1968 R. M. COOPER ET AL 3,390,070 ELECTRODE ADJUSTMENT MEANS FOR MERCURY CATHODE ELECTROLYTIC CELLS Filed Feb. 19, 1965 s Sheets-Sheet 2 INVENTORS. ROY M. COOPER WILL MM C. CARD/IVER BY JAMES R. NEWBERR K Awa /m4 7 AGENT June 1968 R. M. COOPER ET AL 3,390,070

ELECTRODE ADJUSTMENT MEANS FOR MERCURY CATHODE ELECTROLYTIC CELLS Filed Feb. 19, 1965 3 Sheets-Sheet S INVENTORS. ROY M COOPER WILLIAM C. CARD/NE]? JAMES R. NEWBERRY AGENT United States Patent 3,390,070 ELECTRODE ADJUSTMENTS MEANS FDR MERQURY CATHODE ELECTROLYTIQ CELLS Roy M. Cooper, Hamden, William C. Gardiner, Orange, and James R. Newberry, Cheshire, Conn, assignors to ()lin Mathieson Chemical Corporation, a corporation of Virginia Filed Feb. 19, 1965, Ser. No. 434,017 Claims. (Cl. 204-219) This invention relates to cells for the electrolysis of aqueous solutions. More particularly the invention relates to new apparatus for the adjustment of the elevation of anodes in horizontal mercury cells. The invention is particularly applicable to cells of the type described in Us. Patent 3,140,991 but the use of the adjustment means of this invention for anode elevation in other cells is also included within the scope of this invention.

Horizontal mercury cells usually consist of a covered, elongated trough sloping slightly towards one end. The cathode is a flowing layer of mercury which is introduced at the higher end of the cell and flows along the bottom of the cell toward the lower end. The anodes are generally composed of rectangular blocks of graphite suspended from conductive leadins, for example, graphite or protected copper tubes or rods. The bottoms of the graphite anodes are spaced a short distance above the flowing mercury cathode.

In cells of this type, the distance between the graphite anodes and the mercury cathode is very important. This interelectrode distance should be as small as possible to reduce the wasteful consumption of energy, for example, in the production of heat. However, if this distance is too small, secondary reactions take place, particularly the direct attack on sodium amalgam by chlorine bubbles. This distance is ordinarily maintained, if possible in the range of to 4 inch, preferably about ,4; to V inch.

In operation the graphite anodes are consumed thereby increasing the distance between the anodes and cathode and resulting in reduced energy efiiciency. Graphite consumption of the anodes nearer the inlet end of the cell is less than at the outlet end of the cell. To maintain the proper distance between the anodes and cathode, it is necessary to adjust the elevation of the anodes from time to time. In most types of prior art apparatus it is necessary to adjust each anode individually. Adjustment of anodes individually would not be required solely because of graphite consumption since one group of anodes in a cross section of the cell usually are consumed at approximately the same rate. US. Patent 3,140,991 provides for adjustment of a group of anodes arranged in a single cross section of the cell.

One of the objects of this invention is to provide improved means for adjusting the elevation of the anodes in a mercury cathode cell.

Another object of this invention is to provide for the uniform adjustment of a larger group of anodes than is provided in the prior art.

Other objects and advantages of this invention will appear in the course of the following description.

Broadly, the invention resides in improvements in mercury cathode electrolytic cells having a bottom and two sides forming a trough, a perforated, self-supporting cover resting on the sides of said trough, threaded upright members located at spaced intervals on said cover above the sides of said trough, substantially horizontal anodesupporting members having said upright members passing through said horizontal members, threaded support means on said upright members to provide adjustable support for said horizontal members, anodes adjustably suspended from said horizontal members through the Patented June 25, 1968 ice perforations in said cover, a mercury cathode flowing over the bottom of said trough and means for imposing an electric current on said anodes and cathode. In such a mercury cell, the invention resides in the combination therewith of a horizontally rotatable wheel on each of said upright members, endless, flexible drive means engaging a plurality of said wheels and means for rotating said wheels.

Each threaded upright member is provided with a rotatable wheel adapted to effect relative motion of the threaded support means on said threaded upright members. The wheel is suitably a sprocket or suitable type of gear or a flat or V-pulley. The rotatable wheels are adapted to effect relative motion of said threaded support means on said threaded upright members. When one of the wheels is rotated, each of said plurality of wheels in a group of wheels engaged by said drive means also is rotated equally, the effective diameter of the Wheels in that group being equal. The elevation of said horizontal members above said bottom of the cell is thus changed While maintaining said horizontal members substantially parallel to said bottom of the cell.

The upright members are either partially threaded or completely threaded over their entire length. The horizontal anode-supporting members have any suitable form, including fiat plates, T-bars or, advantageously, a channel or angle with the web horizontal and the flanges vertical, extending upward or downward from the web. The horizontal members are advantageously arranged transversely of the cell and the anodes depend therefrom. The threaded means on said upright members provide support for said horizontal members. They have the form of nuts or other suitably threaded means turning on the threaded upright members.

In a first embodiment of the apparatus of this invention, the threaded upright members are stationary and are welded or otherwise attached fixedly to the cell cover. In such embodiment, the threaded means on said threaded upright members support the horizontal members directly or are separated therefrom by suitable electrical insulation. In a second embodiment, the threaded upright members rotate but maintain a fixed elevation with reference to the cell cover. In such embodiment, a suitable thrust cup is fixedly mounted on the cell cover to support and guide the upright member. Threaded support means ride up or down on the threaded upright members, carrying with them the horizontal members in turn supporting the anodes. In a third embodiment, the threaded upright members rotate while the threaded support means bear a fixed relation to the cell cover. The upright members are thereby raised or lowered with reference to the cell cover, Indirectly, via the upright members, the threaded support means provide support for horizontal members having a fixed bearing on the upright members.

In the first embodiment described above in which the upright members are stationary and fixedly attached to the cell cover, the wheels are threaded to match the threads on the upright member or are fixedly attached to a nut or hub so threaded. When the wheel is rotated, it moves up or down on the threaded upright member and carries with it the horizontal anode-supporting member. Insulators, although not essential, are suitably interposed between the horizontal members and the wheels, hubs and upright members.

In the second embodiment in which the upright members rotate but maintain a fixed elevation with reference to the cell cover, the wheel is fixedly attached to the upright member, for example, by keying or by set screws. When the wheel rotates, the upright member rotates and the threaded support means rides up or down on the upright member, carrying with it the horizontal anode-sup- 3 porting member. Appropriate insulators are preferably interposed.

In the third embodiment in which the upright members are vertically movable with reference to the cell cover, each wheel is fixedly attached to an upright member. When the wheel rotates, the upright member is moved vertically by the threaded support means which is fixed relative to the cell cover. A fixed bearing in suitable form, for example, a hub or collar, on the upright member transfers the motion to the horizontal member.

In those embodiments in which the wheel is fixedly attached to an upright member, the wheel is arranged either above or below the level of the threaded support means.

In a preferred form of the invention, the wheels are sprockets which are either threaded to match the threaded upright members or are fabricated as one piece or have a hub welded or keyed to the sprocket. The hub portion is suitably internally threaded to match the threads on the upright members or alternatively is smooth bored and fitted with a key or set screw to lock on a flat portion on the upright member. When the sprocket or hub is threaded, its rotation raises or lowers its position on the upright member. When the sprocket is keyed to the upright member rotation of the sprocket serves to rotate the upright member and raises or lowers the threaded support means on the upright member. The threaded support means in turn, directly or indirectly, raises or lowers the horizontal anode-supporting member and the anodes depending therefrom.

In a particularly preferred embodiment of this invention, an idler, for example, a sprocket is anchored adjustably to a horizontal member, for example, a transverse channel, suitably by a 'bracket attached thereto. Drive means, flexible and endless but not extensible, suitably a chain or mechanical equivalent is passed around the idler and a group, suitably but not necessarily a group of four of the wheels on the upright members. The idler is anchored to tighten the chain or other drive means until the wheels turn easily without any slippage. The idler is the same or a different diameter than the wheels on the upright member.

Using sprockets, with or without an idler, all the sprockets in one group connected by a single chain are advantageously arranged all in the same horizontal plane. That plane in certain embodiments is suitably above or below the plane of the horizontal anode-supporting members.

Roller chain, single or multiple strand, block chain, Reynolds or Morse type chain are useful as drive means with suitably toothed sprockets. Alternatively, hoisting chain, for example, .coil chain, stud-link chain, 90 degree chain or crane chain are useful with suitably grooved or pocketed sheaves. In addition, toothed belting engaging axially grooved face pulleys are positive drives suitable for use in this invention. Further, V-belts and V-belt pulleys sufiiciently tightened to permit no slippage are used but chain is preferred. The term drive means in this specification and in the claims is intended to encompass the mechanical equivalents known to those skilled in the art.

This invention is useful in cells having a plurality of anodes depending from horizontal anode-supporting members. The latter are suitably plates, shafts or bars of any suitable crosssection, for example, T-bars. Particularly advantageous are channels with the flanges either up or down but preferably extending upwardly.

The invention is especially advantageous in cells hav ing large anodes carrying a plurality of lead-ins per anode. An anode 9 x 48 x 6 inches usually carries two lead-ins. Two lead-ins provide more uniform current distribution than can be afforded by a single lead-in for an anode of these dimensions. Two lead-ins also provide more adequate support to maintain the bottom of the anode parallel to the underlying flowing mercury cath ode. To facilitate the flow of brine and chlorine through the cell, the anodes are advantageously arranged with the longer dimension parallel to the length of the cell. One lead-in for any one anode is supported on a transverse channel adjacent the channel supporting the other lead-in for that anode. In adjusting anodes thus supported, it is critical that both lead-ins be moved at the same rate and to the same extent to avoid twisting and loosening the lead-ins and/or breaking the frangible graphite anodes. The adjustment means of this invention insures equal motion of both lead-ins for any one anode.

Current to the anodes is supplied via the anode-supporting members or a separate and insulated system of buses and conductors is alternatively provided. Where the anode-supporting members are also the current-carrying members, insulators are provided between the horizontal anode-supporting members and any conductively attached parts, for example, brackets, on the one hand and the sprockets, chains and upright members on the other hand to permit manual adjustment. Insulators are suitably formed of plastic materials which are non-conductive and preferably which resist frictional wear. Teflon (a polymer of tetrafluoroethylene) and Micarta (a compressed, fabric-reinforced, phenolformaldehyde resin material) are examples of suitable materials. Insulators are suitably formed of tubular elements to which one or more washers are applied as flanges. Alternatively, where only one flange is required, the flange is suitably molded integrally with the tubular portion as a shoulder thereon.

In operation, rotation of the drive sprocket also rotates the four sprockets at the ends of a pair of horizontal members. This elevates or lowers the pair of horizontal members and the anodes depending therefrom are raised or lowered equally. Since graphite consumption is more rapid near the outlet end of the cell, the adjustment of a pair of horizontal members and their depending anodes near the outlet end of the cell is more frequent and the degree is of a magnitude greater than the adjustment of the horizontal members and their depending anodes near the inlet end of the cell.

Rotation of one, and thus all, of the wheels in a group of four or more is suitably manual, by hand on chain, by crank, by means of a rod placed in radial openings in one of the hubs, by socket wrench on a shaped, e.g., square or hexagonal top on any of the spindles or upright members, when the latter are arranged to rotate. Alternatively the means of rotating the wheels is suitably a portable pneumatic tool or an electric motor geared to or driving directly any of the spindles or rotatable upright members.

In addition to the advantages of the apparatus of the present invention in adjusting anode elevation in normal operation, further advantages accrue in start-up operations. Then the entire plant of many cells is appropriately made ready with brine and mercury flowing and all parts in operating position except that the anode-cathode gap is /2 inch or greater. The current is applied and each group of anodes is quickly and easily brought into operating position.

A further advantageous feature is employed by calibrating one or more wheels with a scale to indicate the amount of movement of the anodes, based on the pitch of the threads and the ratio of the diameters of the wheels.

FIGURE 1 shows one embodiment of the apparatus of this invention. Partly in section and partly in view, FIG- URE 1 shows a mercury cell including a portion of one anode having two anode posts, one post depending from each of two adjacent channels. The cell has a bottom 11 and a top 12 between which is anode 13. Anode 13 is supported by anode lead-ins 14 which pass through cover 12 behind upright members 15 and depend from channels 16. Upright members 15 are threaded into nuts 17 welded to cover 12. Insulators 18 separate upright members 15 from channels 16. Below channels 16 are sprockets 19 welded to nuts 20. Attached to the side of one of the channels 16 is a bracket 21. Passing through a hole in bracket 21 is spindle 22 supported by collar 23 and insulated from bracket 21 by insulator 24. Below the bracket, idler sprocket 25 is attached to spindle 22 by hub 26. Chain 27 passes around the far side of sprocket 25 and the near sides of sprockets 19. Chain 27 also passes around two sprockets arranged at the far end (not shown) of each of channels 16.

FIGURE 2 is a top view of the same embodiment as shown in FIGURE 1 of the apparatus of this invention. Parts identical with those of FIGURE I bear the same numbers. FIGURE 2 shows two channels 16, each supported at each end by upright members 15. The plane of sprockets 19 and 25 lies below the plane of the web of channels 16. Chain 27 passes around the four sprockets 19 located near the ends of each of the two channels 16 and around idler sprocket 25.

FIGURE 3 shows one of a plurality of threaded upright members forming another embodiment of the apparatus of this invention. Horizontal anode-supporting members 31 (one shown) are insulated by insulator 32, having the form of a tubular element with a washer attached as a flange, from threaded upright member 33 and hub 34 attached to sprocket 35. Hub 34 is rigidly attached to member 33 by means of set screw 36 hearing on a flattened sur face of member 33. Below the level of sprocket 35, member 33 is threaded and passes through a nut 37 welded to and supported by angles 38 in turn welded to cell cover 12. Attached to one flange of horizontal member 31 is bracket 21 carrying therethrough spindle 22 supporting sprocket 25. Hub 23 above flange 21 and hub 26 below flange 21 retain spindle 22 passing through the flange. The spindle and hubs are insulated from bracket 21 by insulator 24 composed of a tubular element and a washer above and a washer below flange 21. Chain 27 engages the teeth of sprockets 25 and 35 and three additional sprockets of the type of sprocket 35 located on and similarly attached to three additional upright members (not shown) located near the ends of channel 31 and a corresponding adjacent channel (not shown). One of the angles 38 may be omitted when the remaining angle is designed to support adequately the upright member 33 and attached parts. Upright member 33 is not threaded above the level of channel 31 but is threaded below the level of channel 31.

FIGURE 4 shows one of a plurality of threaded upright members forming another embodiment of the apparatus of this invention. The horizontal anode-supporting members are channels 41 (one shown) and are supported on Micarta nuts 42 internally threaded to fit the threads on upright member 44 and having an upward square cut projection 43 passing through a corresponding square cut hole in channel 41. The Micarta nut with projection 43 serves as a guide, supports channel 41 and insulates member 44 from the channel. Attached to the unthreaded lower portion of member 44 is hub 45 carrying sprocket 46. The hub 45 and the lower end of member 44 rest on thrust bearing 47. Spaced along cover 12 thrust bearing 48 supports the hub 49 and sprocket 425. By means of chain 27, sprocket 425 drives sprocket 46 and three additional sprockets similarly constructed and attached to three additional members 44 (not shown). Alternative drive means represented by electric motor 490 serve to operate sprocket 425 and the several sprockets 46 chained together forming a group.

FIGURE 5 shows one of a plurality of threaded upright members forming another embodiment of the apparatus of this invention. Channel 51 is supported on Micarta nut 42 in the same manner as described in FIGURE 4. Square cut projection 43 inserted in a square cut hole in member 51 prevents rotation of Micarta nut 42. Above the level of channel 51, in an unthreaded portion, member 53 carries sprocket 54 fastened rigidly to member 53 by means of hub 55 and set screw 52. The lower end of member 53 is unthreaded, fitted with collar 57, rests in and is supported by thrust bearing 56. Spaced along cell cover 12 is thrust bearing 58 supporting spindle 59 and collar 549. Spindle 59 extends upwardly through insulator 24 supported in flange 21. Spindle 59 carries near its upper end sprocket 525 attached to the spindle by means of hub 526. Chain 27 engages sprockets 525, 54 and three additional sprockets arranged similarly to sprocket 54 on three additional members 53 located at the ends of an adjacent pair of channels 51.

FIGURE 6 shows one of a plurality of threaded upright members forming another embodiment of the apparatus of this invention. Upright member 53 and attached parts are constructed as in FIGURE 5. However, spindle 61 and collar 62 are supported in thrust bearing 63 located on top of pedestal 64, resting on cell cover 12. Pedestal 64 is in one alternative a solid block of metal or in other alternatives constructed of girders or angle iron.

EXAMPLE A battery of mercury cathode cells was constructed for a chlorine-caustic plant. Each cell was about 4 /2 feet wide by about 40 feet long and contained 50 anodes. The anodes were 9 x 48 x 6 inch blocks of graphite. Each anode was supported by two lead-in posts depending from bus feed channels of copper. One anode lead-in post of each pair on any one anode was supported from one bus teed channel and the other anode lead-in post was supported on an adjacent bus feed channel. The channels ran transversely of the cell and were spaced 24 inches between centers. Each channel was 7 x 3% X inch thick, drilled through the web to receive five anode lead-in posts, 9% inches between centers. The anode lead-in posts were locked into place with a nut above and a nut below the channel on threads on each lead-in. The channels were supported on threaded jacking screws at each end of each channel. The jacking screws were attached to the cell cover by nuts welded to the cover. Sprockets were welded coaxially to nuts and threaded on to the jacking screws. Tubular Micarta insulators with shoulders were slipped over the jacking screws and electrically insulated the jacking screws, sprockets and nuts from the channels. One of the channels of each pair supported a bracket and an idler sprocket fitted with a spindle having the upper end milled for reception of a crank. Tubular Teflon insulators fitted with Teflon washers separated the idler sprocket and spindle from the bracket and channel. A roller bearing chain was arranged around the four sprockets on the two upright members and around the idler sprocket as shown in FIGURE 1 so that four sprockets turned clockwise when the idler sprocket was turned counter-clockwise. Current was supplied to the anodes by flexible copper conductors attached to each channel. The circuit was closed by supplying current to the cell bottom.

In use each cell was supplied with brine and mercury at its upper end and depleted brine, amalgam and chlorine were removed from its lower end. The amalgam was decomposed with water to form aqueous caustic and the mercury was returned to the cell. Depleted brine was dechlorinated, resaturated, purified and returned to the cell. In the course of several months operation, adjustment of the height of the anodes above the mercury cathode was greatly simplified. Each group of 5 anodes was satisfactorily adjusted as a unit by applying a crank to the spindle of the idler sprocket. Weekly adjustment was sufficient to maintain the anodes at a distance of inch from the mercury cathode, the distance most eflicient for these cells. Only occasionally was it necessary to adjust an individual anode.

What is claimed is:

1. In a mercury cathode electrolytic cell having:

(a) a bottom and two sides forming a trough;

(b) a perforated, self-supporting cover resting on the sides of said trough;

(c) threaded upright members located at spaced intervals on said cover above the sides of said trough;

(d) substantially horizontal anode-supporting members having said upright members passing through said horizontal members;

(e) threaded support means on said upright members to provide adjustable support for said horizontal members;

(f) anodes adjustably suspended from said horizontal members through the perforations in said cover; a mercury cathode flowing over the bottom of said trough and means for imposing an electric current on said anodes and cathode;

the combination therewith of:

(a) a horizontally rotatable wheel on each of said upright members;

(b) endless, flexible drive means engaging a plurality of said wheels; and

(0) means for rotating said Wheels.

2. The combination of claim 1 in which each of said Wheels is a sprocket and said drive means is a roller chain.

3. The combination of claim 1 in which an idler engages said drive means.

4. The combination of claim 1 in which said horizontal members are current-carrying members and electrical insulators are interposed between said horizontal members and said upright members.

5. The combination of claim 1 in which said drive means engages four of said wheels located on upright members at the ends of a pair of adjacent horizontal members.

References Cited UNITED STATES PATENTS 2,617,762 11/1952 Basilewsky 204225 2,784,157 3/1957 Deprez 204--219 3,052,618 9/1962 Deprez et a1. 204 219 3,140,991 7/1964 Gardiner 204225 HOWARD S. WILLIAMS, Primary Examiner. D. R. VALENTINE, Assistant Examiner. 

1. IN A MERCURY CATHODE ELECTROLYTIC CELL HAVING: (A) A BOTTOM AND TWO SIDES FORMING A TROUGH; (B) A PERFORATED, SELF-SUPPORTING COVER RESTING ON THE SIDES OF SAID TROUGH; (C) THREADED UPRIGHT MEMBERS LOCATED AT SPACED INTERVALS ON SAID COVER ABOVE THE SIDES OF SAID TROUGH; (D) SUBSTANTIALLY HORIZONTAL ANODE-SUPPORTING MEMBERS HAVING SAID UPRIGHT MEMBERS PASSING THROUGH SAID HORIZONTAL MEMBERS; (E) THREADED SUPPORT MEANS ON SAID UPRIGHT MEMBERS TO PROVIDE ADJUSTABLE SUPPORT FOR SAID HORIZONTAL MEMBERS; (F) ANODES ADJUSTABLY SUSPENDED FROM SAID HORIZONTAL MEMBERS THROUGH THE PERFORATIONS IN SAID COVER; A MERCURY CATHODE FLOWING OVER THE BOTTOM OF SAID TROUGH AND MEANS FOR IMPOSING AN ELECTRIC CURRENT ON SAID ANODES AND CATHODE; THE COMBINATION THEREWITH OF: (A) A HORIZONTALLY ROTATABLE WHEEL ON EACH OF SAID UPRIGHT MEMBERS; (B) ENDLESS, FLEXIBLE DRIVE MEANS ENGAGING A PLURALITY OF SAID WHEELS; AND (C) MEANS FOR ROTATING SAID WHEELS. 